Discussion of the 60 year total ozone record at Arosa based on measurements of the vertical distribution and a meteorological parameter

On G. M. B. Dobson's initiative, ozone measurements were started by Götz at Arosa, Switzerland, in 1926, which led to the longest total ozone record in the world over 60 years. Later these measurements were supplemented by Umkehr observations, also at Arosa, and by ozone soundings at Payerne, Switzerland, yielding the concurrent vertical distribution which allows among other things to distinguish between regional and hemispheric scale processes influencing total ozone. Using a meteorogical parameter a method is developed which allows the extension of this distinction to the early period without measurements of the vertical distribution, although with somewhat larger uncertainty. On this basis the ozone variations over Arosa during the past 60 years are discussed.

The ozone loss around the level of the ozone maximum contributed most to the strong decline in the total amount observed between 1970 and 1988. High loss rates were further detected in the upper stratosphere, extending down into the middle stratosphere. While the upper stratospheric decrease is very probably largely a consequence of the CFC input into the atmosphere the loss at the lower level seems to be only partly due to that reason, but in its main contribution to be produced by circulation changes. About one-third of the stratospheric ozone decline is compensated by rapidly rising concentrations in the troposphere caused by increasing air pollution.